1. Field of the Invention
This invention generally relates to the field of signal transmission line structure, and more particularly, to a multilayer complementary-conducting-strip transmission line (thereinafter called CCS TL) structure.
2. Description of the Prior Art
The successfully transmission-line-based (TL-based) hybrid designs for system-on-chip (SOC) integration are relied on for high-efficiency miniaturization. Numerous design techniques and circuit implementations had been reported and demonstrated for the desired circuit requirements. By either using capacitive loading (M. C. Scardelletti, G. E. Ponchak, and T. M. Weller, “Miniaturized Wilkinson power dividers utilizing capacitive loading,” IEEE Microwave Wireless Compon. Lett., vol. 12, no. 1, pp. 6-8, January 2002.) or inductive loading (K. Hettak, G. A. Morin, and M. G. Stubbs, “Compact MMIC CPW and asymmetric CPS branch-line coupler and Wilkinson dividers using shunt and series stub loading,” IEEE Trans. Microwave Theory and Tech., vol. 53, no. 5, pp. 1624-1635, May 2005.), the physical transmission line length in hybrid, coupler, and power divider designs can be reduced by at least 60%.
On the other hand, the well-published technique, so-called the 3-D MMIC technology (K. Nishikawa, T. Tokumitsu, and I. Toyoda, “Miniaturized Wilkinson power divider using three-dimensional MMIC technology,” IEEE Microwave Guided Wave Lett., vol. 6, no. 10, pp. 372-374, October 1996.; C. Y. Ng, M. Chongcheawchamnan, I. D. Robertson, “Lumped-distributed hybrids in 3D-MMIC technology,” IEEE Proc. -Microwave. Antennas and Propag., vol. 151, no. 4, pp. 370-374, August 2004.; I. Toyoda, T. Tokumitsu, and M. Ailawa, “Highly integrated three-dimensional MMIC single-chip receiver and transmitter,” IEEE Trans. Microwave Theory Tech., vol. 44, no. 12, pp. 2340-2346, December 1996.), has shown the fundamental breakthrough on multilayer transmission line implementations using GaAs technology. In the 3-D MMIC designs, the upper and lower lines are shielded by the intermedia metal with the slit. The size of the slit can be applied to control the coupling and characteristic impedances of two transmission lines. Such implementation had been widely applied to the 3-D miniaturized designs of power divider (K. Nishikawa, T. Tokumitsu, and I. Toyoda, “Miniaturized Wilkinson power divider using three-dimensional MMIC technology,” IEEE Microwave Guided Wave Lett., vol. 6, no. 10, pp. 372-374, October 1996.), hybrid (C. Y. Ng, M. Chongcheawchamnan, I. D. Robertson, “Lumped-distributed hybrids in 3D-MMIC technology,” IEEE Proc. -Microwave. Antennas and Propag., vol. 151, no. 4, pp. 370-374, August 2004.), and high-density integrated transceiver (I. Toyoda, T. Tokumitsu, and M. Ailawa, “Highly integrated three-dimensional MMIC single-chip receiver and transmitter,” IEEE Trans. Microwave Theory Tech., vol. 44, no. 12, pp. 2340-2346, December 1996.).
Recently, the multilayer design technique has been applied to microwave/millimeter-wave CMOS distributed passive components (M. Chirala, and C. Nguyen, “Multilayer Design Techniques for Extremely Miniaturized CMOS Microwave and Millimeter-Wave Distributed Passive Circuit,” IEEE Trans. Microwave Theory Tech., vol. 54, no. 12, pp. 4218-4224, December. 2006.). The microwave/millimeter-wave rat-race hybrid is designed by incorporating the multilayer microstrip lines. The reference ground plane is realized by the uniform bottom metal in CMOS processes. The signal traces can be arranged in the meandered-form and no extra shielding metal is inserted between upper and lower microstrip lines. Hence, between upper and lower microstrip lines, there has no any effective signal shield.
In view of the drawbacks mentioned with the prior art of signal transmission line, there is a continuous need to develop a new and improved multilayer CCS TL structure that overcomes the disadvantages associated with the prior art. The advantages of the present invention are that it solves the problems mentioned above.